IPv6 Prefix Delegation using ICMPv6
Currently proposed solution for IPv6 Prefix Delegation is based on DHCPv6 protocol. We believe that in certain network topologies and configurations where the CPE routers may not be capable or configured to use DHCPv6 and hence can not utilize the currently proposed ipv6 prefix delegation procedure. Therefore an alternate ipv6 prefix delegation procedure that does not require or depend on the DHCPv6 protocol is needed. This document proposes an ICMPv6 based prefix delegation (PD) mechanism as an alternative to the DHCPv6 based prefix delegation mechanism in conformance with RFC 3769 which describes the requirements for IPv6 prefix delegation. This proposal involves using the Router Solicitation (RS) message for the prefix request and the Router Advertisement(RA) message for the prefix delegation. A new flag called P-flag (bit 0 of the reserved field) is defined to indicate that the RS message includes a PD request. RS messages with PD request can now include PIO option(s) to carry PD information such as prefix preference(s) or PD parameters such as lease etc. It also proposes defining a new flag called D-flag (reserved bit 26) of the PIO option to indicate the presence of PD specific PIO in RS and RA messages.